1. Field of the Invention
The present invention relates to an image forming apparatus and more specifically to an image forming apparatus loaded with a sleep mode.
2. Description of Related Art
In an image forming apparatus, a paper feed part is provided which supplies paper to an image forming part where an image is formed. The paper feed part includes a paper cassette that stores paper. The paper cassette is detached from the image forming apparatus upon paper storage. Then after the paper storage into the paper cassette, it is attached to the image forming apparatus.
Moreover, in terms of power consumption saving, a normal mode and a sleep mode are typically loaded in the image forming apparatus. The normal mode corresponds to a state in which a temperature of a fixing roller is kept at a temperature appropriate for fixing developer such as a toner and thus image formation can be performed immediately upon acceptance of an image formation request. Thus, the normal mode is a mode with high power consumption. On the other hand, the sleep mode corresponds to a state in which temperature of the fixing roller is higher than a room temperature but kept lower than that in the normal mode and thus the image formation cannot be performed immediately upon the acceptance of the image formation request, thus requiring some time from when the fixing roller heats up to when it reaches an appropriate temperature. Therefore, the sleep mode is a mode with lower power consumption than that in the normal mode.
The image forming apparatus shifts to the sleep mode after staying in standby for predetermined time without accepting the image formation request during operation in the normal mode. Moreover, the image forming apparatus deactivates the sleep mode upon acceptance of the image formation request during operation in the sleep mode. That is, it shifts to the normal mode.
As described above, the image forming apparatus loaded with the sleep mode is disclosed in, for example, JP-A-2002-172832 and JP-A-2003-291460.
According to JP-A-2002-172832, the image forming apparatus deactivates a sleep mode upon detachment of a paper cassette during operation in the sleep mode. Then after calculation of the number of pieces of paper inside the paper cassette, the image forming apparatus shifts again to the sleep mode.
Also in JP-A-2003-291460, the image forming apparatus deactivates a sleep mode upon detachment of a paper cassette during operation in the sleep mode.
With the technologies disclosed in JP-A-2002-172832 and JP-A-2003-291460, at a stage at which the paper cassette is detached, the sleep mode is deactivated and shift to the normal mode occurs. In that case, for example, even when the paper cassette is left in a continuously detached state for predetermined time, there is a risk of wasteful power consumption.